Shock-proof nylon carpet system

ABSTRACT

A SHOCK-PROOF CARPET SYSTEM HAVING A FACE YARN OF TEXTURED NYLON CONTAINING UP TO ABOUT TWELVE WEIGHT PERCENT OF AN INTERNAL ADDITIVE SELECTED FROM ETHYLENE OXIDE CONDENSATION PRODUCTS, A PRIMARY BACKING OF JUITE OR SPUNBONDED SYNTHETIC MATERIAL WITH OR WITHOUT METAL FIBERS WOVEN INTO THE SAID BACKNG, A TUFT-LOCKING LATEX MADE ELECTRICALLY CONDUCTIVE BY THE ADDITIVE OF UP TO ABOUT TEN WEIGHT PERCENT OF AN ANTISTATIC MATERIAL AND/OR HAVING A FINE GAUGE METLLIC FILM, SCREEN, OR A MAT OF METAL FIBERS IMBEDDED THEREIN, AND A STANDARD SECONDARY BACKING

pied State P t t :SHOCIGPROOF NYLON -GARPET SYSTEM t.- .(;hem' a C n enon M rr o'wt NJ No D wing.'Fil'e'd July 19, 19 72, Ser. No. 273,064

13 Claims ABsTRAcTor'iTIiE' DISCLOSURE CROSS'REFERENOE APPLICATIONS Thisapplication is relatedtoi 'copending applications,

centini 'and'Genef o defw eaonj and Ser. No. 239,373, filep Ma r. 29,1912 by Ronald E.. Rothwell, Cipriano 'Rusliand are hereby incorporatedbyreferepceinto application.

naertenomo ORV-THE INVENTION misinvention-relates to a. shockrproofcarpet system based onnylon...More.- particularly -it relates to animproved. carpet; system based on nylon made shock-proof by oi certainadditives. And, still moreparticularly -it relates tma-carpetfsystem.based on'nylon made shockproofby use-of-radditives that actually improveits shock proofness as the carpet systernwears.

Carpet systems are well'ldiotiv n'to generate considerablechargesof:-statie elect:ricity: when ,a person in contact therewithtraversestheearpetsystems fibrous layer. Such charges are-quitenaturally-iransfer'r'ed to the person trayersingsaid carpetsystem and.upon. grounding, the charges are discharged causing momentary. shockanda source of pensionable irritation.-,And,;although several carpetsystems have been devisedirt an effort to improve this system, all tendto becoriie 'less and'l'e ss viable with use. One sdhf'static-dis'chargingzfloor covering. system is disclosed in-UaS.ltat.-'2;?-l2,()03 wherein a coating of a flexible elect'nieallycoatingmaterial; such'asiambber compound condarbon blaclgis aflixedtotthe underside of a rug, and a phtralit t ofgelectricaliy conductingelements, such as cotton cords, and; an electr ically conductive rubbercomposition are used'which com into contact with theterating-aridthtis'itenfi' to"substantially the top of the rug. Anothermoreaecem approach to solving this problem of static charge buildup inacarpet system is-described in US. Pat. 3, 28, l- 7 .wherein up to about10 percent by weight on a continuous carpet system iscomprisedbt-metauie fibrs'in 'c'ontiinious metalto 'metal conthesolutionoi thisistatic buildup a'c'oating-'ori thdbatking c'ontacting'the face -fiber; this '5 Ice coating also containing an additive toreduce buildup of static electricity and metallic-conductors contactingthe backing or the coating. A prime objectof this invention is toprovide a permanent shock-proof carpet system. Another object of thisinvention is to provide a permanent shock-proof nylon carpet system. Afurther object of this invention is to provide a permanent shock-proofnylon carpet system ,wherein the additives utilized in making suchcarpet system are maintained and utilizable in the carpet systemthroughout the life of the carpet system. A still further object of thisinvention is to provide a permanent shock-proof nylon carpet systemwherein the static electricity buildup is lower than the threshold ofsensitivity to humans. And, a still further object of this invention isto provide a permanent shockproof nylon carpet system wherein the staticelectricity buildup gets actually lower or improves its shock-proofelfectiveness with normal use. Other objects will appear hereinafter asthe description of the invention proceeds.

The above and other objects of this invention are ac complished inpreparing an antistatic textile article comprising a fibrous textilelayer of the pile type, said pile being prepared froma polyamide fibercontaining between about 1 percent and about 12 percent by weight of apredominantly branched, chain-extended polymer of the reaction productof a compound represented by the formula:

.where a, b, c, d, w, x, y, and z are each a whole number and R is adifunctional radical from a hydrocarbon containing 1 to 13 carbon atoms,and at least one compound selected from the group consisting ofdiepoxidesand compounds which yield the following divalent radicals:

o 0 0 H H 0 where R is a difunctional radical derived from aromatic,heterocyclic, cycloaliphatic or aliphatic hydrocarbons or combinationsof them having said fibrous pile secured to a primary backing, a. finegauge metallic screen or mat of metal fibers, and an adhesive conductivelatex backing added thereto. The. adhesive" conductive latex is madeconductive by containing up to ten weight percent of said latex from acompound selected from the group consisting of the reaction product of acompound represented by the formula:

on: on, n ocn,cn, obncm)., (cnlbIron crncrnonn on, NRN cI-n .HocIIloHi).(Q norms on, Honwmcmona where a, b, c, d, w, x, and z are eacha whole number and R is a difunctonal radical from a-hydrocarboncontaining 1 to lt3'carbon-atoms, and at least one compound selectedfromfithe group-consisting of *diepoxidesand compoun whiehyie-ld' thetollowingdivalent radicals: I

" "-0" o o It' Ir'o' 1 LL: :ll H' .l I. ll

fg -T f' 39 -'T where .-R-is,a"difunctional radical derived fromaromatic, heterocyclic, .cycloaliphatic or aliphatic hydrocarbons orcombinations of them having-said fibrous pile secured to a primarybacking,xand an adhesive conductive latex backing added thereto andpolyethylene-oxide.

The antistatic fiber of this invention can contain certain conventionaladditives without any adverse effects upon the overall shock-proofcarpet system of this invention. That is, the carpet system of thisinvention is compatible in all instances with other additives, naturallyeither necessary or desirable, such as, dyeing assists and colorants,stabilizers, antioxidants and delustrants among others.

The fine gauge metallic screen can be prepared from any ductileconductive material, such as various steel alloys, copper, etc.

Surprisingly, such improved shock-proof carpet system of this inventionnot only provides a shock-proof carpet system initially below thethreshold of sensitivity to humans, but actually improves itsshock-proof effectiveness with use. Such threshold of sensitivity tohumans has been established at between approximately about 2,500 toabout 4,000 volts. See Modern Textiles, April 1971 publication, articleA Shock-Free Carpet System at 10% Relative Humidity and papers of theAmerican Association For Textile Technology, Inc. by D. H. Martin, R. D.Radford and K. R. Lea. Another static test procedures for textiles isdescribed in technical bulletin No. 2-015, dated Mar. 1, 1970 byBrunswick Corporation, Technical Products Div., 69 W. Washington, St.,Chicago, Ill. 60602. These publications also illustrate the walk-testmethod employed in static electricity buildup evaluation. These testmethods are somewhat redundant, but do complement each other to a greatextent. They do agree that a static level greater than about 3 kilovoltsor 3,000 volts, as measured by these tests, will produce a shockdetectable by most people and objectionable to some.

The principles of practicing the invention are further illustrated bythe following examples, but without limiting the invention to thedetails thereof.

EXAMPLE 1 Polycaproamide polymer is used having a moisture content of0.05% to 0.10%, total constituents extractable by hot water of 1% to 2%,and formic acid relative viscosity of 62. The polymer contains about0.2% titanium dioxide dulling agent, antioxidant, and 6% of anantistatic agent consisting of a polyether of dimethylterephthalate andTetronic 1504 supplied by Wyandotte and covered under US. Pat. 2,979,528by Lunsted. The Tetronic 1504 is one of many tetrol compoundscommercially available as tetronic series block copolymers havingmolecular weights between 1,650 and 26,000. This series varies in lengthof poly(oxyethylene) chain and poly(oxypropylene) chain. A 3 and 4 digitcode numbed indicates the molecular composition. When four digits areemployed, the first two explain the average molecular weight of thehydrophobe (poly(oxypropylene) branches on the alkylenediamine). Whenthree digits are used only the first number serves this purpose. Thelast digit of each code number represents the weight percentage ofhydrophilic (poly(oxyethylene) units to the nearest 10% The antistaticmaterial is metered at the hopper with the polycaproamide polymer andboth are fed into a screw extruder having an exit temperature of 260 C.The polymer is forwarded at a pressure of 1,900 p.s.i.g. through a sandfilter to a spinnerette plate with 70 holes, each of which is 0.95 inchdeep and 0.025 inch in diameter. The freshly extruded filaments descenda spinning tower into which air conditioned at 70 F. and 65% relativehumidity is admitted. The yarn emerging from the spinning tower contactsa ceramic roll applies a lubricant finish, and the yarn then is woundonto a package at 1,850 feet per minute. The yarn thus obtained has adenier of 3,150, is drawn over a /3; inch diameter draw pin at adelivery rate of 1,536 feet per minute which is 3.01 times the feed ratein order to obtain a drawn yarn denier of 1,050 denier. Each of the 70filament has a denier of 15. During drawing the yarn is passed 5 wrapsover a shoe-type heater maintained at 175 C. The yarn is then subjectedto a continuous stutter box crimping operation and two ends of 1,050denier are combined and 4 twisted together to produce a 2,250 denier,filament With a 8" type twist yarn. e

The yarn is then employed in making a level loop pile tufted carpethaving twenty ounces of fiber per square yard of carpet and employing aspun-bonded polypropylene backing scoured, dyed at 212 F, rinsed anddried. The carpet is then double backed with a latex consisting ofstyrene butadiene rubber having five weight percent of low molecularweight polyethylene oxide antistatic material. The antistatic propertiesof this carpet as determined by the Walk Test method wherein thetemperature is controlled at 71 F. and the relative humidity iscontrolled at 20% are compared in Table I with control carpets.

TABLE I Walk Test. maximum voltage generated (kv.)

After Alter 20M 40M Sample Initial treads treads Control carpet (regularyarn-regular latex) l4. 4 Carpet with internal antistat yarn as definedin this invention 5. 8 5. 7 5. 6 Carpet with internal antistat yarn asdefined in this invention in combination with latex containing liveweight percent v polyethylene oxide antistatic materiaL- 2. 3 2. 3 2. 3Carpet with internal antistat. yarn as defined in this invention incombination with latex containing five weight percent of the internalantistat used in the yarn 2. 2 2. 2 2.

EXAMPLE 2 2,200-l40 denier textured nylon 6 yarn containing 6% of apolyether of DMT and Tetronic 1504 and 0.2% of anti-oxidant was tuftedon Typar primary backing into 20 oz./yd. level loop carpet. The carpetwas subsequently piece dyed in a dye bath and dried. A fine gauge steelscreen was then added to the backing of the carpet while this wassimultaneously back-coated with Uniroyal Latex GX-2179, astyrenebutadiene base latex containing an electrically conductivematerial. After Locktuft secondary backing was added and the carpetcured, the. carpet was tested for static generation according to theWalk Test Method. Results of the test showed that the static voltagegenerated at 21 C. and 20% RH. was below 3,000 volts.

EXAMPLE 3 As in Example 1, with the exception that the metal screen wasreplaced with metal fibers uniformly dispersed in the Uniroyalconductive latex prior to carpet coating, the metal fibers having adiameter of 0.01-0.05 inch and a length of 1 inch retained fiber tofiber contact in the cured latex sandwiched between the two carpetbackings.

EXAMPLE 4 As in Example 2, with the exception that metal filamentshaving a diameter of 0.01-0.5 inch were woven into primary and secondarybackings prior to the application of the conductive latex. Metal tometal contact was maintained in the carpet backing structures.

EXAMPLE 5 As in Example 2, with the exception that nylon 2.0/1 to 4.0 2"yarn spun from staple was used to produce 32 oz./yd. plush carpet.

EXAMPLE 6 As in Example 2, with the exception that nylon was used.

EXAMPLE 7 washing and drying, the polymer was processed as in Example 1.The maximum voltage generated in kv. in the Walk Test is 2.4 intially.It shows 2.2 after 20M treads and 2.0 after 40M treads.

EXAMPLE 8 As in Example 1, except that 400 ends of undrawn yarn arecombined into a tow. The tow is drawn, crimped and cut into 6.5 inchlong staple, all in a continuous operation. The staple is then spun intoa 2.25 with 3.5 Z twist and converted into 40 oZ./yd. cut pile plus typecarpets. The maximum voltage generated in kv. in the Walk Test is 2.3.After 20M treads it dropped to 2.2 and after 40M treads it dropped to2.01.

EXAMPLE 9 As in Example 1, except that nylon 6,6 polymer is used.Continuous and staple yarns are prepared and the results in the carpetswere as follows: initial kv. is 2.9; after 20M treads, 2.1 kv.; andafter 40M treads the kv. is 1.5.

EXAMPLE 10 As in Example 1, except the yarn internal antistatic additiveis added in an amount of 10 weight percent of the polymer. The resultingmaximum voltage in the carpet is equivalent to results in Table 1.

EXAMPLE 11 As in Example 1, except the yarn internal antistatic additiveis also used in the conductive latex. The resulting maximum voltage inthe carpet is equivalent to results in Table I.

The products of this invention are useful for many purposes, forexample, for more or less routine type carpeting areas having about 35%RH. (relative humidity). This invention can be used wherein just thefiber has the antistat additive therein and the carpet system yields asystem having a static level less than about 3 kilovolts or 3,000 volts,that is, a shock level undetectable by most people.

Where the carpet system need is much greater for static free carpetsystems, for example, about RH. (relative humidity) this invention canbe used wherein the fiber and the conductive latex having the antistatadditive therein yields a carpet system having a static level less thanabout 3 kilovolts or 3,000 volts, that is, a shock level undetectable bymost people.

Where the reduction in static by a carpet system is essential, hospitaloperating rooms, computer rooms, explosive areas, etc. then, thisinvention can be used wherein the fiber, the conductive primary andsecondary backing has the antistat additive therein of this invention aswell as a fine gauge metallic screen, film or mat of metal fibersbetween said backings.

It is to be understood that although the instant invention has beendescribed as set forth herein in a preferred form, obviously numerousmodifications can be made without parting from the scope and spiritthereof, and such modifications are to be understood as coming withinthe scope of the appended claims.

We claim:

1. In a textile article comprised of a polyamide face fiber containingan additive to reduce buildup of static electricity,

a backing having said face fiber secured thereto,

a coating on said backing contacting said face fiber, said coating alsocontaining an additive to reduce buildup of static electricity, and

metallic conductors contacting said backing or said coating,

the improvement consisting essentially of using for said adidtive toreduce buildup of static electricity in said face fiber between about 1percent and about 12 percent by weight of a predominantly branchedchain-extended compound represented by the formula where a, b, c, d, w,x, y, and z are each a whole number and R is a difunctional radical froma hydrocarbon containing 1 to 13 carbon atoms, and at least one compoundselected from the group consisting of diepoxides and compounds whichyield the following divalent radicals:

O O O H H 0 1.1.12 indent where R is a difunctional radical derived fromaromatic, heterocyclic, cycloaliphatic or aliphatic hydrocarbons orcombinations of them, whereby said textile article will generate lessthan 3 kilovolts of static electricity by the walk test and the staticelectricity buildup gets lower with normal use of said textile article.

2. The article of claim 1 wherein the polyamide is selected from thegroup consisting of polycaproamide and polyhexamethylene adipamide.

3. The article of claim 1 wherein the backing is styrene butadienerubber latex.

4. The article of claim 1 wherein said metallic conductors are ametallic mat made of conductive metal fibers uniformly dispersed in theconductive latex.

5. The article of claim 2 wherein said metallic conductors are ametallic screen woven into said primary and backing.

6. The article of claim 2 wherein said metallic conductors are ametallic screen having metal to metal contact in the carpet backingstructures.

7. The article of claim 1 wherein said metallic material is made offilaments having a diameter of from about 0.01 to 0.5 inch.

8. The article of claim 1 wherein said polyamide fiber is nylon 6.

9. The article of claim 1 wherein said polyamide fiber is nylon 6,6.

10. The article of claim 1 wherein the additive in said coating of claim1 is also the additive in said face fiber of claim 1.

11. The article of claim 10 wherein said face fiber is secured to saidbacking by extending through to the back side of said backing and saidcoating on said backing is on the back side of said backing.

12. The article of claim 11 wherein a secondary backing is added tocover said coating on said backing having said face fiber securedthereto.

13. The article of claim 12 wherein said primary backing is selectedfrom the group consisting of synthetic material or jute and saidsecondary backing is a material selected from the group consisting ofspun bonded or woven polypropyl material or jute.

References Cited UNITED STATES PATENTS 3,510,386 5/1970 Goins et a116167 3,554,824 1/1971 Callahan 161-66 3,582,445 1/ 1971 Okuhashi 16l-673,702,797 11/1972 Cochran 16167 3,713,960 1/ 1973 Cochran 161--673,719,547 3/1973 Martin et a1. 161-67 3,728,205 4/ 1973 Brindell et al.161-67 WILLIAM J. VAN BALEN, Primary Examiner US. Cl. X.R. 161-227P@-\250 v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONInventor(s) Ronald Edward Rothwell and Cioriano Cipri ani It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 33, part of formula "N (OCH CH 2 (IOgHCH should be--H(OCH CH z (QSHCH 2 Column 2, line 59, after letter "x" insert -y-.

Column 3, line 20, "procedures" should be -procedure- Column 4, Table I,line 28, under column "After 40M Treads", "2" should be -2.2.

Column 4, line 51, insert -anafter "of" econd oocur'renc e Column 6,line 4 in formula (CH CH O) H" should be (CH CH O) H:-.

Signed and sealed this 31st day of December 1974.

(SEAL) v Attest:

MCCOY 'M. GIBSCN JR. C. MARSHALL DANN Attesting Officer I Commissionerof Patents

